3. Autonomic effects—

Autonomic effects result from blockade of peripheral muscarinic receptors and α adrenoceptors and are more difficult to manage in elderly patients. Tolerance to some of the autonomic effects occurs with continued therapy. Of the older antipsychotic agents, thioridazine has the strongest autonomic effects and haloperidol the weakest. Clozapine and most of the atypical drugs have intermediate autonomic effects.